Make StackArray Implementation Generic

[rachitbhalla]

The StackArray is implemented using integer array and can hold only integer values. However, it can be modified using Generics to hold value of any type.

[Andreas-White]

Do you need help with the generic issue? I could give it a try.

[ayaankhan98]

Do you need help with the generic issue? I could give it a try.

That PR is quite old, see if the author respond to that or else you can make a new PR for this.

[stale]

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[stale]

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